Dew shield mock up for 90% humidity shoot

[Tom OD]

If you are having dew forming on your lens while out imaging this might help. Given the large area and amount of “glass” in wide field lens your night can end quickly once dew starts to form. Wiping it off just is not enough as it ll form again quickly.
I was using a 60mm dew heater strap for a telescope. I bought some speaker connectors and 9v connectors online and soldered them up. This worked great and cleared dew from the 14mm glass. It’s small light and compact but if you re out all night you ll need to use two or three 9v batteries. A better option would be a 12v moped re-chargeable battery if weight is not an issue.
I was imaging in 90% humidity and needed to go a step further. One of our party had foam fold up cushions. I got duct tape and made my own dew box. With a section cut out I was able to get to see through the view finder and adjust any dials. There was no vignetting and this kept the dew off all night. The outside of the box was dripping wet.
A slight breeze helps keep the dew off, and if you can avoid standing too far out in the open. Try sheltering by trees as this prevents dew forming too. Hope you find this useful.